<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    <ul>
      <li  v-for="(item,index) in movies" @click="changeColor(index)" :class="{active:index==changeIndex}">{{item}}</li>
    </ul>
  </div>
  <script src="./js/vue.js"></script>
  <script>
    const app=new Vue({
      el:'#app',
      data:{
        changeIndex:0,
        movies:['西游记','红楼梦','水浒传','聊斋志异']
      },
      methods: {
        changeColor(index){
          this.changeIndex=index
        }
      },
      
    })
  </script>
</body>
<style>
  .active{
    color:red
  }
</style>
</html>